'\" t
.TH "SD_BUS_SET_FD" "3" "" "systemd 257~rc3" "sd_bus_set_fd"
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.SH "NAME"
sd_bus_set_fd \- Set the file descriptors to use for bus communication
.SH "SYNOPSIS"
.sp
.ft B
.nf
#include <systemd/sd\-bus\&.h>
.fi
.ft
.HP \w'int\ sd_bus_set_fd('u
.BI "int sd_bus_set_fd(sd_bus\ *" "bus" ", int\ " "input_fd" ", int\ " "output_fd" ");"
.SH "DESCRIPTION"
.PP
\fBsd_bus_set_fd()\fR
sets the file descriptors used to communicate by a bus connection object\&. Both
\fIinput_fd\fR
and
\fIoutput_fd\fR
must be valid file descriptors, referring to stream\-based file objects (e\&.g\&. a stream socket, a pair of pipes or FIFOs, or even a TTY device)\&.
\fIinput_fd\fR
must be readable, and
\fIoutput_fd\fR
must be writable\&. The same file descriptor may be used (and typically is used) as both the input and the output file descriptor\&. This function must be called before the bus connection is started via
\fBsd_bus_start\fR(3)\&.
.PP
The bus connection object will take possession of the passed file descriptors and will close them automatically when it is freed\&. Use
\fBsd_bus_set_close_on_exit\fR(3)
to turn off this behaviour\&.
.SH "RETURN VALUE"
.PP
On success,
\fBsd_bus_set_fd()\fR
returns a non\-negative integer\&. On failure, it returns a negative errno\-style error code\&.
.SS "Errors"
.PP
Returned errors may indicate the following problems:
.PP
\fB\-EINVAL\fR
.RS 4
An invalid bus object was passed\&.
.sp
Added in version 248\&.
.RE
.PP
\fB\-ECHILD\fR
.RS 4
The bus connection was allocated in a parent process and is being reused in a child process after
\fBfork()\fR\&.
.sp
Added in version 248\&.
.RE
.PP
\fB\-EBADF\fR
.RS 4
An invalid file descriptor was passed to
\fBsd_bus_set_fd()\fR\&.
.sp
Added in version 248\&.
.RE
.PP
\fB\-ENOPKG\fR
.RS 4
The bus cannot be resolved\&.
.sp
Added in version 248\&.
.RE
.PP
\fB\-EPERM\fR
.RS 4
The bus connection has already been started\&.
.sp
Added in version 248\&.
.RE
.SH "NOTES"
.PP
Functions described here are available as a shared library, which can be compiled against and linked to with the
\fBlibsystemd\fR\ \&\fBpkg-config\fR(1)
file\&.
.PP
The code described here uses
\fBgetenv\fR(3), which is declared to be not multi\-thread\-safe\&. This means that the code calling the functions described here must not call
\fBsetenv\fR(3)
from a parallel thread\&. It is recommended to only do calls to
\fBsetenv()\fR
from an early phase of the program when no other threads have been started\&.
.SH "HISTORY"
.PP
\fBsd_bus_set_fd()\fR
was added in version 248\&.
.SH "SEE ALSO"
.PP
\fBsystemd\fR(1), \fBsd-bus\fR(3), \fBsd_bus_get_fd\fR(3), \fBsd_bus_start\fR(3)
